1. Field of the Invention
The present invention relates to a heat-sealing device for sheet packages that presses and seals onto a bag-forming film a lid unit component that allows sheets stored in the bag to be taken out.
2. Description of Related Art
Conventionally, a wet-tissue package has been known as an example of a package of sheets where wet tissues are stored in the package in a manner retrievable one by one from the take-out opening (refer to Patent Literature 1). The wet-tissue package has a structure shown in FIGS. 6 and 7, where FIG. 6 is an oblique view of the wet-tissue package, while FIG. 7 is a longitudinal section view of the wet-tissue package in FIG. 6 cut along the II-II line.
The structure of the wet-tissue package is explained by referring to FIGS. 6 and 7.
Symbol 1 indicates a bag, while 2 indicates a lid unit component, where a wet-tissue stack 3 is stored inside the bag 1 having this lid unit component 2, as shown in FIG. 7.
The bag 1 can be made of any material which is air-tight, such as polyethylene, polypropylene, polyester, polyamide or any other plastic film capable of preventing the chemical agent, cosmetic or any other substance impregnated in the wet tissues from oozing out or volatilizing.
The lid unit component 2 is installed on the top bag surface in a manner covering the opening 4 provided in the top surface of the bag 1, wherein a contact part where the top surface along the periphery 6a of the substrate of the component 2 contacts the bottom surface of the circumference 4a of the opening 4 is connected by a joining method such as heat sealing to securely adhere the component 2 onto the top surface of the body 1 in a manner covering the opening 4.
FIG. 8 is a schematic drawing showing a process of manufacturing wet-tissue packages by joining, via heat sealing, a bag-forming film 26 with a lid unit component 2 into one piece and then packaging wet tissues inside.
As one example of the manufacturing process for wet-tissue packages, a process where wet-tissue packages are obtained through steps A to F, as shown in FIG. 8, is known (refer to FIG. 13 of Patent Literature 1). According to this manufacturing process, a bag-forming film 26 constituted by an air-tight film material is continuously fed from a feeding device in step A in such a way that the inner side of the bag faces out, and then in step B a hole of an appropriate size is punched out in the film using a stamping device 27 to form an opening 4, after which a lid unit component 2 is fed in step C with the component 2 placed over the formed surface of the opening in the film and temporarily attached there, and finally in step D the heat-sealing device 28 is applied from the back of the film 26 and the heating plate of the heat-sealing device 28 is pressed onto the circumference of the opening 4 to join the film 26 and lid unit component 2 into one piece by heat sealing.
Wet-tissue packages are obtained by:                folding wet tissues constituted by sheet materials made of paper, etc., that have been impregnated with a chemical agent, etc., stacking them into multiple layers in such a way that the ends of adjacent tissues are overlapping one another, and feeding the resulting wet-tissue stack 3 to be placed on top of the formed lid unit component surface of the film 26, in step E;        wrapping the wet-tissue stack 3 with the film 26 using a bagging device, joining the overlapping part 5a of the film 26 at the center by a joining method such as heat sealing, while also joining the overlapping parts 5b, 5c formed at both ends of the overlapping part 5a at the center in the same manner by a joining method such as heat sealing, to form a bag, in step F; and        further using a heated blade 29 to cut along the boundary between adjacent bags that have been manufactured consecutively in the manner, to separate the bags.        
As shown in FIG. 8, the heat-sealing device 28 used in step D mentioned above is applied from the back of the film 26 in such a way that the heating plate of the heat-sealing device 28 is pressed against the circumference of the opening 4 to join the film 26 and lid unit component 2 into one piece by heating, etc. This conventional heat-sealing device 28 uses a rotary motor as a drive source to produce back-and-forth motion, where generally a ball screw mechanism is used for this conversion of rotary motion into back-and-forth motion. Although not illustrated, a pressing device that presses against and sandwiches the film 26 on the heat-sealing device 28 is provided above, and when a lid unit component 2 placed on a film 26 arrives the pressing device comes down and simultaneously the heat-sealing device 28 moves up to sandwich the film 26 and lid unit component 2, and in this condition the lid unit component 2 is thermally set onto the film 26 and the two become one piece in approx. 2 seconds, after which the pressing device moves up and simultaneously the heat-sealing device 28 comes down until both the pressing device and heat-sealing device 28 return to their original positions, and the operations are performed repeatedly. In one minute, the device is able to join a bag-forming film with approx. 20 lid unit components placed on top of the film.
It should also be noted that the needs for sheet packages of various types, sizes and other characteristics are increasing, but no heat-sealing device is known that can manufacture sheet packages according to these needs for various types and sizes.
[Patent Literature 1] U.S. Pat. No. 5,729,955, Specification